Some help needed. How to check whether the existing propeller meets the specs? EG 400x280 means 400mm diameter (that is simple) and 280 is the pitch. How is the pitch measured?? Any experience with flex couplings such as Vetus Bullflex or Uniflex? Has the shaft to be shortened and is the flange to the gearbox standard or heavy machining involved? (I have a Kawasaki (Hurth) KM3-A gearbox. Help is very much appreciated.